This invention relates generally to an incandescent lamp filament mount construction and more particularly to physical support means for a hollow open-ended transparent cylinder coated with an infrared reflecting film and surrounding the lamp filament which also centers the filament within the cylinder.
An already known means to increase the efficacy or operating efficiency of an incandescent lamp is to surround the filament light source with an open-ended transparent cylinder coated with an infrared reflecting film. Such a lamp construction is disclosed in U.S. Pat. No. 4,517,491, which is assigned to the assignee of the present invention, and the particular lamp construction incorporating such efficiency improvement means is a tungsten-halogen lamp. In one embodiment, the hollow transparent cylinder is provided with a sufficient size internal opening so as to further incorporate one of the lead-in conductors connected to the lamp filament and with the cylinder being physically supported within the lamp envelope by an outward protruding bulge provided in said lead-in conductor. In an alternate embodiment, this lead-in conduct extends longitudinally outside the cylinder with an inward protruding bulge section providing physical support thereto by urging the cylinder against an inner wall of the lamp envelope.
Centering of the lamp filament within the coated cylinder so as to provide a coaxial alignment therebetween is of considerable importance. For the infrared coating on the cylinder to be effective it is essential for the reflected energy to be focused back upon the lamp filament. For this optical criteria to be satisfied, it becomes understandably further necessary that the lamp filament be precisely located at the cylinder center since even minor deviations therefrom causes the reflected infrared rays not to impinge upon the filament. Considerable lamp efficacy losses are encountered due to any misalignment thereby further dictating that a precise coaxial alignment between the lamp filament and coated cylinder be maintained throughout the operating lamp life. While it becomes possible for some infrared rays which do not impinge upon the lamp filament to be subsequently redirected to the filament after multiple reflections, there will be considerable efficacy losses experienced with such mode of lamp operation.
Accordingly, it is an object of the present invention to provide improved means for accurate filament orientation within a coated cylinder providing higher operating efficiency in a tungsten-halogen lamp.
It is another object of the present invention to provide improved means whereby the lamp filament is more precisely centered within a coated cylinder employed to improve efficacy in a tungsten-halogen lamp.
Still another object of the present invention is to provide a tungsten-halogen lamp employing a cylinder coated with an infrared reflecting film which cooperates more effectively with the lamp filament to provide greater lamp operating efficiency.
Still another object of the present invention is to provide an improved reflector lamp employing an inner tungsten-halogen lamp as the light source wherein the tungsten-halogen lamp imparts higher operating efficiency to the overall lamp construction.
These and other objects of the present invention will become more apparent upon consideration cf the following detailed description for the present invention.